Remote activation systems for detonating explosives have been used widely in the field of military and industrial demolition applications. In the past, demolition initiation devices have been used to generate an electrical impulse for initiating detonation. For example, a blasting cap used in conjunction with an explosive charge (e.g., C4) can be electrically connected to output terminals of the initiation device using electrical conductors. In many instances, the conductors can be several hundred meters long to separate the initiation device and the explosive. In this arrangement, the assembly is sensitive to electrical conditions, such as electromagnetic interference (EMI) and/or electrostatic discharge (ESD). As a result of this sensitivity, premature detonation of the explosive charge has been known to occur with unacceptable frequency. The results of premature detonation can include unintended damage and/or unintended personal injury or death.
At least one attempt has been made to avoid using electrical conductors to deliver explosion initiating energy from the initiation device to the explosive change. In this attempt a mechanical arm driven by a solenoid was used to initiate a device that propagates a chemical reaction from initiator to explosive. As used herein, chemical reaction or chemical energy includes the burning or exploding of a given material.
Such an attempt is described in U.S. Pat. No. 6,546,873, which discloses a transmitter that transmits a detonation signal to a receiver. The receiver can be configured to deliver an electrical output in response to a received detonation signal. Such electrical output can be used to electrically excite a blasting cap via conductors. But, as indicated above, if the conductors have any appreciable length (e.g., 50 meters or more), ambient electrical conditions (e.g., an atmospheric electrical storm) can cause premature detonation of the explosive. The receiver can alternatively be used to actuate the solenoid/mechanical arm assembly mentioned above. However, electrical signals output by the RAMS receiver have low power levels and testing by the Army Research Lab has determined that solenoid based mechanical actuators do not perform with enough reliability to be deployed in the field.
Accordingly, there exists a need in the art for an explosion initiating assembly that has reduced sensitivity to electrical conditions and can reliably initiate a chemical energy propagation assembly when powered by a low level electrical power source.